Film and digital photography (including both still and video) generally cannot reproduce the entire available dynamic range range of a scene. As a result, photographers have always had to find an acceptable balance, trading off highlight details for more shadow details and vice versa. The issue is exacerbated with most digital cameras since the single-chip color image sensors used in most digital cameras have a lower dynamic range than most film.
Recently, high dynamic range (“HDR”) digital imaging has become popular, producing images with considerable tonal range throughout the color gamut. Typically, such HDR imaging employs two or more captures at varying exposures (e.g, using exposure bracketing or with the help of a flash). The bracketed exposures are then stitched together (using post-capture, post-demosaicking image processing software) to create a single image having a much greater dynamic tonal range than is possible in a single image capture with the particular sensor employed. In other words, an HDR image is recovered from multiple low dynamic range (“LDR”) images which together comprise a set of overdetermined observations which collectively provide an adequate coverage of the dynamic range. Though exposure bracketing is typically implemented as a “time multiplexing” of exposure rates, capturing moving objects poses a particular challenge. These time multiplexing techniques also preclude HDR video and handheld camera applications.
Single-shot (i.e., single, non-bracketed exposure) HDR alternatives have been proposed as a way to capture HDR images, particularly for HDR imaging of nonstationary objects. For instance, an exposure mosaicking and assorted pixel arrangement has been proposed for implementing spatially varying pixel exposures. Multisensor and alternative pixel architecture solutions have also been proposed. However, these single-shot HDR solutions require a special purpose or modified hardware.
While a variety of devices and techniques may exist for HDR imaging, it is believed that no one prior to the inventor has made or used an invention as described herein.
The drawings and images are not intended to be limiting in any way, and it is contemplated that various embodiments of the invention may be carried out in a variety of other ways, including those not necessarily depicted in the drawings and images. The accompanying drawings and images incorporated in and forming a part of the specification illustrate several aspects of the present invention, and together with the description serve to explain the principles of the invention; it being understood, however, that this invention is not limited to the precise arrangements shown.